/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date:        19. March 2015
* $Revision: 	V.1.4.5
*
* Project: 	    CMSIS DSP Library
* Title:	    arm_cfft_radix2_f32.c
*
* Description:	Radix-2 Decimation in Frequency CFFT & CIFFT Floating point processing function
*
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* -------------------------------------------------------------------- */

#include "arm_math.h"

void arm_radix2_butterfly_f32(
    float32_t *pSrc,
    uint32_t fftLen,
    float32_t *pCoef,
    uint16_t twidCoefModifier);

void arm_radix2_butterfly_inverse_f32(
    float32_t *pSrc,
    uint32_t fftLen,
    float32_t *pCoef,
    uint16_t twidCoefModifier,
    float32_t onebyfftLen);

extern void arm_bitreversal_f32(
    float32_t *pSrc,
    uint16_t fftSize,
    uint16_t bitRevFactor,
    uint16_t *pBitRevTab);

/**
* @ingroup groupTransforms
*/

/**
* @addtogroup ComplexFFT
* @{
*/

/**
* @details
* @brief Radix-2 CFFT/CIFFT.
* @deprecated Do not use this function.  It has been superseded by \ref arm_cfft_f32 and will be removed
* in the future.
* @param[in]      *S    points to an instance of the floating-point Radix-2 CFFT/CIFFT structure.
* @param[in, out] *pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.
* @return none.
*/

void arm_cfft_radix2_f32(
    const arm_cfft_radix2_instance_f32 *S,
    float32_t *pSrc)
{

    if(S->ifftFlag == 1u)
    {
        /*  Complex IFFT radix-2  */
        arm_radix2_butterfly_inverse_f32(pSrc, S->fftLen, S->pTwiddle,
                                         S->twidCoefModifier, S->onebyfftLen);
    }
    else
    {
        /*  Complex FFT radix-2  */
        arm_radix2_butterfly_f32(pSrc, S->fftLen, S->pTwiddle,
                                 S->twidCoefModifier);
    }

    if(S->bitReverseFlag == 1u)
    {
        /*  Bit Reversal */
        arm_bitreversal_f32(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
    }

}


/**
* @} end of ComplexFFT group
*/



/* ----------------------------------------------------------------------
** Internal helper function used by the FFTs
** ------------------------------------------------------------------- */

/*
* @brief  Core function for the floating-point CFFT butterfly process.
* @param[in, out] *pSrc            points to the in-place buffer of floating-point data type.
* @param[in]      fftLen           length of the FFT.
* @param[in]      *pCoef           points to the twiddle coefficient buffer.
* @param[in]      twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
* @return none.
*/

void arm_radix2_butterfly_f32(
    float32_t *pSrc,
    uint32_t fftLen,
    float32_t *pCoef,
    uint16_t twidCoefModifier)
{

    uint32_t i, j, k, l;
    uint32_t n1, n2, ia;
    float32_t xt, yt, cosVal, sinVal;
    float32_t p0, p1, p2, p3;
    float32_t a0, a1;

#ifndef ARM_MATH_CM0_FAMILY

    /*  Initializations for the first stage */
    n2 = fftLen >> 1;
    ia = 0;
    i = 0;

    // loop for groups
    for (k = n2; k > 0; k--)
    {
        cosVal = pCoef[ia * 2];
        sinVal = pCoef[(ia * 2) + 1];

        /*  Twiddle coefficients index modifier */
        ia += twidCoefModifier;

        /*  index calculation for the input as, */
        /*  pSrc[i + 0], pSrc[i + fftLen/1] */
        l = i + n2;

        /*  Butterfly implementation */
        a0 = pSrc[2 * i] + pSrc[2 * l];
        xt = pSrc[2 * i] - pSrc[2 * l];

        yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
        a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

        p0 = xt * cosVal;
        p1 = yt * sinVal;
        p2 = yt * cosVal;
        p3 = xt * sinVal;

        pSrc[2 * i]     = a0;
        pSrc[2 * i + 1] = a1;

        pSrc[2 * l]     = p0 + p1;
        pSrc[2 * l + 1] = p2 - p3;

        i++;
    }                             // groups loop end

    twidCoefModifier <<= 1u;

    // loop for stage
    for (k = n2; k > 2; k = k >> 1)
    {
        n1 = n2;
        n2 = n2 >> 1;
        ia = 0;

        // loop for groups
        j = 0;
        do
        {
            cosVal = pCoef[ia * 2];
            sinVal = pCoef[(ia * 2) + 1];
            ia += twidCoefModifier;

            // loop for butterfly
            i = j;
            do
            {
                l = i + n2;
                a0 = pSrc[2 * i] + pSrc[2 * l];
                xt = pSrc[2 * i] - pSrc[2 * l];

                yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
                a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

                p0 = xt * cosVal;
                p1 = yt * sinVal;
                p2 = yt * cosVal;
                p3 = xt * sinVal;

                pSrc[2 * i] = a0;
                pSrc[2 * i + 1] = a1;

                pSrc[2 * l]     = p0 + p1;
                pSrc[2 * l + 1] = p2 - p3;

                i += n1;
            }
            while( i < fftLen );                          // butterfly loop end
            j++;
        }
        while( j < n2);                            // groups loop end
        twidCoefModifier <<= 1u;
    }                             // stages loop end

    // loop for butterfly
    for (i = 0; i < fftLen; i += 2)
    {
        a0 = pSrc[2 * i] + pSrc[2 * i + 2];
        xt = pSrc[2 * i] - pSrc[2 * i + 2];

        yt = pSrc[2 * i + 1] - pSrc[2 * i + 3];
        a1 = pSrc[2 * i + 3] + pSrc[2 * i + 1];

        pSrc[2 * i] = a0;
        pSrc[2 * i + 1] = a1;
        pSrc[2 * i + 2] = xt;
        pSrc[2 * i + 3] = yt;
    }                             // groups loop end

#else

    n2 = fftLen;

    // loop for stage
    for (k = fftLen; k > 1; k = k >> 1)
    {
        n1 = n2;
        n2 = n2 >> 1;
        ia = 0;

        // loop for groups
        j = 0;
        do
        {
            cosVal = pCoef[ia * 2];
            sinVal = pCoef[(ia * 2) + 1];
            ia += twidCoefModifier;

            // loop for butterfly
            i = j;
            do
            {
                l = i + n2;
                a0 = pSrc[2 * i] + pSrc[2 * l];
                xt = pSrc[2 * i] - pSrc[2 * l];

                yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
                a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

                p0 = xt * cosVal;
                p1 = yt * sinVal;
                p2 = yt * cosVal;
                p3 = xt * sinVal;

                pSrc[2 * i] = a0;
                pSrc[2 * i + 1] = a1;

                pSrc[2 * l]     = p0 + p1;
                pSrc[2 * l + 1] = p2 - p3;

                i += n1;
            }
            while(i < fftLen);
            j++;
        }
        while(j < n2);
        twidCoefModifier <<= 1u;
    }

#endif //    #ifndef ARM_MATH_CM0_FAMILY

}


void arm_radix2_butterfly_inverse_f32(
    float32_t *pSrc,
    uint32_t fftLen,
    float32_t *pCoef,
    uint16_t twidCoefModifier,
    float32_t onebyfftLen)
{

    uint32_t i, j, k, l;
    uint32_t n1, n2, ia;
    float32_t xt, yt, cosVal, sinVal;
    float32_t p0, p1, p2, p3;
    float32_t a0, a1;

#ifndef ARM_MATH_CM0_FAMILY

    n2 = fftLen >> 1;
    ia = 0;

    // loop for groups
    for (i = 0; i < n2; i++)
    {
        cosVal = pCoef[ia * 2];
        sinVal = pCoef[(ia * 2) + 1];
        ia += twidCoefModifier;

        l = i + n2;
        a0 = pSrc[2 * i] + pSrc[2 * l];
        xt = pSrc[2 * i] - pSrc[2 * l];

        yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
        a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

        p0 = xt * cosVal;
        p1 = yt * sinVal;
        p2 = yt * cosVal;
        p3 = xt * sinVal;

        pSrc[2 * i] = a0;
        pSrc[2 * i + 1] = a1;

        pSrc[2 * l]     = p0 - p1;
        pSrc[2 * l + 1] = p2 + p3;
    }                             // groups loop end

    twidCoefModifier <<= 1u;

    // loop for stage
    for (k = fftLen / 2; k > 2; k = k >> 1)
    {
        n1 = n2;
        n2 = n2 >> 1;
        ia = 0;

        // loop for groups
        j = 0;
        do
        {
            cosVal = pCoef[ia * 2];
            sinVal = pCoef[(ia * 2) + 1];
            ia += twidCoefModifier;

            // loop for butterfly
            i = j;
            do
            {
                l = i + n2;
                a0 = pSrc[2 * i] + pSrc[2 * l];
                xt = pSrc[2 * i] - pSrc[2 * l];

                yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
                a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

                p0 = xt * cosVal;
                p1 = yt * sinVal;
                p2 = yt * cosVal;
                p3 = xt * sinVal;

                pSrc[2 * i] = a0;
                pSrc[2 * i + 1] = a1;

                pSrc[2 * l]     = p0 - p1;
                pSrc[2 * l + 1] = p2 + p3;

                i += n1;
            }
            while( i < fftLen );                   // butterfly loop end
            j++;
        }
        while(j < n2);                        // groups loop end

        twidCoefModifier <<= 1u;
    }                             // stages loop end

    // loop for butterfly
    for (i = 0; i < fftLen; i += 2)
    {
        a0 = pSrc[2 * i] + pSrc[2 * i + 2];
        xt = pSrc[2 * i] - pSrc[2 * i + 2];

        a1 = pSrc[2 * i + 3] + pSrc[2 * i + 1];
        yt = pSrc[2 * i + 1] - pSrc[2 * i + 3];

        p0 = a0 * onebyfftLen;
        p2 = xt * onebyfftLen;
        p1 = a1 * onebyfftLen;
        p3 = yt * onebyfftLen;

        pSrc[2 * i] = p0;
        pSrc[2 * i + 1] = p1;
        pSrc[2 * i + 2] = p2;
        pSrc[2 * i + 3] = p3;
    }                             // butterfly loop end

#else

    n2 = fftLen;

    // loop for stage
    for (k = fftLen; k > 2; k = k >> 1)
    {
        n1 = n2;
        n2 = n2 >> 1;
        ia = 0;

        // loop for groups
        j = 0;
        do
        {
            cosVal = pCoef[ia * 2];
            sinVal = pCoef[(ia * 2) + 1];
            ia = ia + twidCoefModifier;

            // loop for butterfly
            i = j;
            do
            {
                l = i + n2;
                a0 = pSrc[2 * i] + pSrc[2 * l];
                xt = pSrc[2 * i] - pSrc[2 * l];

                yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
                a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

                p0 = xt * cosVal;
                p1 = yt * sinVal;
                p2 = yt * cosVal;
                p3 = xt * sinVal;

                pSrc[2 * i] = a0;
                pSrc[2 * i + 1] = a1;

                pSrc[2 * l]     = p0 - p1;
                pSrc[2 * l + 1] = p2 + p3;

                i += n1;
            }
            while( i < fftLen );                      // butterfly loop end
            j++;
        }
        while( j < n2 );                        // groups loop end

        twidCoefModifier = twidCoefModifier << 1u;
    }                             // stages loop end

    n1 = n2;
    n2 = n2 >> 1;

    // loop for butterfly
    for (i = 0; i < fftLen; i += n1)
    {
        l = i + n2;

        a0 = pSrc[2 * i] + pSrc[2 * l];
        xt = pSrc[2 * i] - pSrc[2 * l];

        a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];
        yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];

        p0 = a0 * onebyfftLen;
        p2 = xt * onebyfftLen;
        p1 = a1 * onebyfftLen;
        p3 = yt * onebyfftLen;

        pSrc[2 * i] = p0;
        pSrc[2u * l] = p2;

        pSrc[2 * i + 1] = p1;
        pSrc[2u * l + 1u] = p3;
    }                             // butterfly loop end

#endif //      #ifndef ARM_MATH_CM0_FAMILY

}
